1. Field of the Invention
The invention relates to a motor vehicle gate lock, especially a tailgate lock having a lock catch which can be shifted from an open position into a catch position and vice versa, and a detent pawl which holds the lock catch in the catch position by catching and which has an actuating surface for the lock catch at a distance from a catch projection. More specifically, the invention relates to such a motor vehicle gate lock which also has an electric motor drive with a drive element and a driving lug located off-center thereto, the driving lug touching the actuating surface of the detent by rotation of the drive element in one direction for lifting the catch projection of the detent pawl out of the catch projection of the lock catch, the lock catch keeping the detent pawl in a raised position when it is in the open position.
2. Description of Related Art
The known motor vehicle gate lock on which the invention is based (German Patent 39 32 268) is suitable as a gate lock, especially for a tailgate or rear door, but also as a hood lock or door lock. In the prior art, it is explained using the example of a tailgate lock or rear door lock. These motor vehicle locks, which are operated with an electric motor opening drive, are especially important in fact for rear doors of station wagons, but also for tailgates of standard sedans.
In the known motor vehicle gate lock, there is an elastic stop for the detent pawl in its raised position. As soon as the detent pawl has reached the elastic stop, and thus its up position, the electric motor drive is turned off. The drive element, which is made as a disk and which represents the worm wheel of an electric motor worm drive, is turned around its axis of rotation by a pretensioned reset spring in the backwards direction, and in this way, is returned to its initial position. The driving lug thus returns, with the reverse running direction, to its initial position on the same path on which it has approached the actuating surface of the detent pawl as it moves away and has moved the pawl into the up position. If the tailgate is then closed, the lock latch releases the detent pawl so that it can return to the lowered position under the action of the springs located between the two.
In the above described motor vehicle gate lock, the electric motor drive must lift not only the detent pawl but, at the same time, it must also tension the reset spring of the worn wheel. Therefore, it must be made accordingly strong.
From the prior art, a corresponding motor vehicle gate lock or motor vehicle door lock is known (Published German Application 32 42 527) in which lifting of the detent pawl by means of an eccentric driving lug takes place such that the drive element always turns in only one direction, and therefore, is not set back, the driving lug, after the detent pawl has been raised, running past its actuating surface. Therefore, here, the driving lug does not return to its initial position in a backwards motion, but runs through a complete 360 degree arc back into its initial position; when the latter is reached, a microswitch turns off the electric motor drive.
In the initially explained prior art, it is feasible for the disengagement of the electric motor drive to be triggered by monitoring the power consumption of the electric motor drive as soon as the detent pawl strikes the elastic stop. This is a better idea than using microswitches which can always fail.